Neurocysticercosis: validity of ELISA after storage of whole blood and cerebrospinal fluid on paper

Cysticercosis is an infestation of Cysticercus cellulosae. When it occurs in the brain, chronic neurological complications can ensue, most commonly seizures. Neurocysticercosis is usually diagnosed by neuroimaging, a technique not available in most endemic countries. Hence immunological tests are valuable for diagnosis and epidemiological surveys. We evaluated the suitability of paper for storing blood and cerebrospinal fluid (CSF) until subsequent testing by enzyme-linked immunosorbent assay (ELISA), by testing whole blood samples on filter paper from 305 patients and CSF samples from 117 patients stored on ordinary white typing paper and on filter paper. Optimal preservation of biological samples is achieved when whole blood is stored on filter paper, CSF on white paper, and when samples are frozen within 1 week after collection. Our results could improve diagnostic capabilities and facilitate epidemiological surveys in endemic countries where immunodiagnostic tests cannot be rapidly performed because of inadequate laboratory infrastructure.